On the quest to remove all VLAs from the kernel[1] this moves buffers off the stack. In the second instance, this collapses two separately allocated buffers into a single buffer, since they are used consecutively, which saves 256 bytes (QUERY_DESC_MAX_SIZE + 1) of stack space. [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@xxxxxxxxxxxxxx Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> --- drivers/scsi/ufs/ufshcd.c | 34 ++++++++++++++++++++++++++-------- 1 file changed, 26 insertions(+), 8 deletions(-) diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c index 00e79057f870..a271534362f6 100644 --- a/drivers/scsi/ufs/ufshcd.c +++ b/drivers/scsi/ufs/ufshcd.c @@ -5958,14 +5958,18 @@ static void ufshcd_init_icc_levels(struct ufs_hba *hba) { int ret; int buff_len = hba->desc_size.pwr_desc; - u8 desc_buf[hba->desc_size.pwr_desc]; + u8 *desc_buf; + + desc_buf = kmalloc(buff_len, GFP_KERNEL); + if (!desc_buf) + return; ret = ufshcd_read_power_desc(hba, desc_buf, buff_len); if (ret) { dev_err(hba->dev, "%s: Failed reading power descriptor.len = %d ret = %d", __func__, buff_len, ret); - return; + goto out; } hba->init_prefetch_data.icc_level = @@ -5983,6 +5987,8 @@ static void ufshcd_init_icc_levels(struct ufs_hba *hba) "%s: Failed configuring bActiveICCLevel = %d ret = %d", __func__, hba->init_prefetch_data.icc_level , ret); +out: + kfree(desc_buf); } /** @@ -6052,9 +6058,17 @@ static int ufs_get_device_desc(struct ufs_hba *hba, struct ufs_dev_desc *dev_desc) { int err; + size_t buff_len; u8 model_index; - u8 str_desc_buf[QUERY_DESC_MAX_SIZE + 1] = {0}; - u8 desc_buf[hba->desc_size.dev_desc]; + u8 *desc_buf; + + buff_len = max_t(size_t, hba->desc_size.dev_desc, + QUERY_DESC_MAX_SIZE + 1); + desc_buf = kmalloc(buff_len, GFP_KERNEL); + if (!desc_buf) { + err = -ENOMEM; + goto out; + } err = ufshcd_read_device_desc(hba, desc_buf, hba->desc_size.dev_desc); if (err) { @@ -6072,7 +6086,10 @@ static int ufs_get_device_desc(struct ufs_hba *hba, model_index = desc_buf[DEVICE_DESC_PARAM_PRDCT_NAME]; - err = ufshcd_read_string_desc(hba, model_index, str_desc_buf, + /* Zero-pad entire buffer for string termination. */ + memset(desc_buf, 0, buff_len); + + err = ufshcd_read_string_desc(hba, model_index, desc_buf, QUERY_DESC_MAX_SIZE, true/*ASCII*/); if (err) { dev_err(hba->dev, "%s: Failed reading Product Name. err = %d\n", @@ -6080,15 +6097,16 @@ static int ufs_get_device_desc(struct ufs_hba *hba, goto out; } - str_desc_buf[QUERY_DESC_MAX_SIZE] = '\0'; - strlcpy(dev_desc->model, (str_desc_buf + QUERY_DESC_HDR_SIZE), - min_t(u8, str_desc_buf[QUERY_DESC_LENGTH_OFFSET], + desc_buf[QUERY_DESC_MAX_SIZE] = '\0'; + strlcpy(dev_desc->model, (desc_buf + QUERY_DESC_HDR_SIZE), + min_t(u8, desc_buf[QUERY_DESC_LENGTH_OFFSET], MAX_MODEL_LEN)); /* Null terminate the model string */ dev_desc->model[MAX_MODEL_LEN] = '\0'; out: + kfree(desc_buf); return err; } -- 2.17.0 -- Kees Cook Pixel Security
